Electronic component

ABSTRACT

An electronic component includes a laminate including a plurality of insulating layers that are laminated on each other. A capacitor conductor is embedded in the laminate and includes an exposed portion exposed between the insulating layers at a predetermined surface of the laminate. An external electrode is provided on the predetermined surface by direct plating so as to cover the exposed portion. An outer edge of the external electrode is spaced away from the exposed portion by about 0.8 μm or more.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an electronic component, and moreparticularly, to an electronic component including a laminate in whichinsulating layers are laminated on each other.

2. Description of the Related Art

A multilayer electronic component of the related art is disclosed inJapanese Unexamined Patent Application Publication No. 2008-47907. Themultilayer electronic component includes a plurality of dielectriclayers, a plurality of internal electrodes, and terminals. Thedielectric layers and the internal electrodes are alternately laminatedon each other. The terminals are external electrodes provided on sidesurfaces of a laminate including the dielectric layers. In themultilayer electronic component described above, the internal electrodesare exposed at the side surfaces of the laminate, and the terminals areformed by plating portions of the laminate at which the internalelectrodes are exposed.

In the above-described multilayer electronic component, a dielectricmaterial may be denatured by absorbing moisture in the air (hereinafter,referred to as “moisture absorption”). As a result, the insulatingproperties of the dielectric layers provided between the internalelectrodes are degraded, and short circuiting may occur therebetween.

SUMMARY OF THE INVENTION

To overcome the problems described above, preferred embodiments of thepresent invention provide an electronic component which preventsdegradation in properties thereof caused by moisture absorption of alaminate.

According to a preferred embodiment of the present invention, anelectronic component is provided which includes a laminate including aplurality of insulating layers laminated to each other, a first internalconductor which is embedded in the laminate and which includes a firstexposed portion exposed between the insulating layers at a predeterminedsurface of the laminate, and a first external electrode provided on thepredetermined surface by direct plating so as to cover the first exposedportion. The first external electrode preferably includes an outer edgethat is spaced away from the first exposed portion by approximately 0.8μm or more, for example.

According to various preferred embodiments of the present invention, theproperties of the electronic component are prevented from being degradedby moisture absorption of the laminate.

The above and other elements, features, steps, characteristics andadvantages of the present invention will become more apparent from thefollowing detailed description of the preferred embodiments withreference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an electronic component according to apreferred embodiment of the present invention.

FIG. 2 is an exploded perspective view of a laminate of the electroniccomponent according to a preferred embodiment of the present invention.

FIG. 3 is a plan view of an external electrode of the electroniccomponent according to a preferred embodiment of the present invention.

FIG. 4 is a cross-sectional view of the electronic component taken alongthe line A-A shown in FIG. 3.

FIG. 5 is a perspective view of an electronic component according to amodified preferred embodiment of the present invention.

FIG. 6 is an exploded perspective view of a laminate of the electroniccomponent according to the modified preferred embodiment of the presentinvention.

FIG. 7 is a perspective view of an electronic component according toanother modified preferred embodiment of the present invention.

FIG. 8 is an exploded perspective view of a laminate of the electroniccomponent according to another modified preferred embodiment of thepresent invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, an electronic component according to preferred embodimentsof the present invention will be described with reference to thedrawings.

First, the structure of an electronic component according to a preferredembodiment of the present invention will be described with reference tothe drawings. FIG. 1 is a perspective view of an electronic component10. FIG. 2 is an exploded perspective view of a laminate 12 of theelectronic component 10. In this preferred embodiment, a laminationdirection of the laminate 12 is defined as a y axis direction. When thelaminate 12 is viewed in plan in the y axis direction, a longer sidedirection of the laminate 12 is defined as an x axis direction. When thelaminate 12 is viewed in plan in the y axis direction, a shorter sidedirection of the laminate 12 is defined as a z axis direction.

As shown in FIGS. 1 and 2, the electronic component 10 is preferably achip capacitor which includes the laminate 12, external electrodes 14 a,14 b, 15 a, and 15 b, and a capacitor C (not shown to FIG. 1). Thelaminate 12 preferably has a substantially rectangular parallelepipedshape, for example. However, since chamfering is performed, the laminate12 preferably has substantially round-shaped corners and ridge lines,for example. Hereinafter, in the laminate 12, a surface at a positivedirection side in the y axis direction is called a side surface S1, anda surface at a negative direction side in the y axis direction is calleda side surface S2. In addition, a surface at a negative direction sidein the x axis direction is called an end surface S3, and a surface at apositive direction side in the x axis direction is called an end surfaceS4. Furthermore, a surface at a positive direction side in the z axisdirection is called an upper surface S5, and a surface at a negativedirection side in the z axis direction is called a lower surface S6.

Furthermore, a shorter side of the side surface S1 at the positivedirection side in the x axis direction is defined as a ridge line L1, alonger side of the side surface S1 at the negative direction side in thez axis direction is defined as a ridge line L2, a shorter side of theside surface S1 at the negative direction side in the x axis directionis defined as a ridge line L3, and a longer side of the side surface S1at the positive direction side in the z axis direction is defined as aridge line L4. In addition, a shorter side of the upper surface S5 atthe positive direction side in the x axis direction is defined as aridge line L5, and a shorter side of the lower surface S6 at thepositive direction side in the x axis direction is defined as a ridgeline L6. A shorter side of the lower surface S6 at the negativedirection side in the x axis direction is defined as a ridge line L7,and a shorter side of the upper surface S5 at the negative directionside in the x axis direction is defined as a ridge line L8. A shorterside of the side surface S2 at the positive direction side in the x axisdirection is defined as a ridge line L9, a longer side of the sidesurface S2 at the negative direction side in the z axis direction isdefined as a ridge line L10, a shorter side of the side surface S2 atthe negative direction side in the x axis direction is defined as aridge line L11, and a longer side of the side surface S2 at the positivedirection side in the z axis direction is defined as a ridge line L12.

As shown in FIG. 2, the laminate 12 is formed by laminating a pluralityof insulating layers 16. Each of the insulating layers 16 preferably hasa substantially rectangular shape and is formed from a dielectricceramic. As an example of the dielectric ceramic, for example, BaTiO₃,CaTiO₃, SrTiO₃, or CaZrO₃ may preferably be used. In addition, at leastone of the materials described above may preferably be used as a primarycomponent, and at least one of a Mn compound, a Fe compound, a Crcompound, a Co compound, and a Ni compound, for example, may preferablybe used as an accessory component. The thickness of the insulating layer16 is preferably set in a range of about 0.5 μm to about 10 μm.Hereinafter, a primary surface of the insulating layer 16 at thepositive direction side in the y axis direction is called a frontsurface, and a primary surface of the insulating layer 16 at thenegative direction side in the y axis direction is called a rearsurface.

As described above, the side surface S1 of the laminate 12 is defined bythe surface of an insulating layer 16 provided at the most positivedirection side in the y axis direction. The side surface S2 of thelaminate 12 is defined by the rear surface of an insulating layer 16provided at the most negative direction side in the y axis direction. Inaddition, the end surface S3 is defined by the shorter sides of theinsulating layers 16 at the negative direction side in the x axisdirection. The end surface S4 is defined by the shorter sides of theinsulating layers 16 at the positive direction side in the x axisdirection. The upper surface S5 is defined by the longer sides of theinsulating layers 16 at the positive direction side in the z axisdirection. The lower surface S6 is defined by the longer sides of theinsulating layers 16 at the negative direction side in the z axisdirection.

As shown in FIG. 2, the capacitor C includes internal capacitorconductors 18 a and 18 b embedded in the laminate 12. It is preferablethat the internal capacitor conductors 18 be made, for example, of aconductive material, such as Ni, Cu, Ag, Pd, a Ag—Pd alloy, or Au, andhave a thickness in a range of about 0.3 μm to about 2.0 μm.

The capacitor conductor 18 a is provided on the surface of oneinsulating layer 16 and preferably includes a capacity portion 20 a andlead portions 22 a and 24 a. The capacity portion 20 a preferably has asubstantially rectangular shape and is not in contact with an outer edgeof the insulating layer 16. The lead portion 22 a preferably protrudestoward the negative direction side in the z axis direction from thevicinity of an end portion at the negative direction side in the x axisdirection of a longer side at the negative direction side in the z axisdirection of the capacity portion 20 a. Accordingly, the lead portion 22a extends to the longer side of the insulating layer 16 at the negativedirection side in the z axis direction. Thus, preferably the leadportion 22 a does not extend to a corner portion of the insulating layer16 and is not provided on the ridge lines L1 to L12 of the laminate 12.At a front end portion at the negative direction side in the zdirection, the lead portion 22 a includes an exposed portion 26 aexposed between adjacent two insulating layers 16 at the lower surfaceS6 of the laminate 12. The lead portion 24 a preferably protrudes towardthe positive direction side in the z axis direction from the vicinity ofan end portion at the negative direction side in the x axis direction ofa longer side at the positive direction side in the z axis direction ofthe capacity portion 20 a. Accordingly, the lead portion 24 a extends tothe longer side of the insulating layer 16 at the positive directionside in the z axis direction. Accordingly, the lead portion 24 a doesnot extend to a corner portion of the insulating layer 16 and is notprovided on the ridge lines L1 to L12 of the laminate 12. At a front endportion at the positive direction side in the z direction, the leadportion 24 a includes an exposed portion 28 a exposed between theadjacent two insulating layers 16 at the upper surface S5 of thelaminate 12.

The capacitor conductor 18 b is preferably provided on the surface ofone insulating layer 16 and includes a capacity portion 20 b and leadportions 22 b and 24 b. The capacity portion 20 b preferably has asubstantially rectangular shape and is not in contact with an outer edgeof the insulating layer 16. In addition, the capacity portion 20 b isarranged to face the capacity portion 20 a with the insulating layer 16interposed therebetween. Accordingly, the capacity is generated betweenthe capacity portions 20 a and 20 b. The lead portion 22 b preferablyprotrudes toward the negative direction side in the z axis directionfrom the vicinity of an end portion at the positive direction side inthe x axis direction of a longer side at the negative direction side inthe z axis direction of the capacity portion 20 b. Accordingly, the leadportion 22 b extends to the longer side of the insulating layer 16 atthe negative direction side in the z axis direction. Thus, the leadportion 22 b does not extend to a corner portion of the insulating layer16 and is not provided on the ridge lines L1 to L12 of the laminate 12.The lead portion 22 b is located at the positive direction side in the xaxis direction than the lead portion 22 a. At a front end portion at thenegative direction side in the z direction, the lead portion 22 bincludes an exposed portion 26 b exposed between the adjacent twoinsulating layers 16 at the lower surface S6 of the laminate 12. Thelead portion 24 b preferably protrudes toward the positive directionside in the z axis direction from the vicinity of an end portion at thepositive direction side in the x axis direction of a longer side at thepositive direction side in the z axis direction of the capacity portion20 b. Accordingly, the lead portion 24 b extends to the longer side ofthe insulating layer 16 at the positive direction side in the z axisdirection. Thus, the lead portion 24 b does not extend to a cornerportion of the insulating layer 16 and is not provided on the ridgelines L1 to L12 of the laminate 12. The lead portion 24 b is preferablylocated at the positive direction side in the x axis direction from thelead portion 24 a. At a front end portion at the positive direction sidein the z direction, the lead portion 24 b includes an exposed portion 28b exposed between the adjacent two insulating layers 16 at the uppersurface S5 of the laminate 12.

The capacitor conductors 18 a and 18 b are preferably provided on 445insulating layers 16, for example, so as to be alternately disposed inthe y axis direction. Accordingly, the capacitor C is provided at aportion at which the capacitor conductor 18 a faces the capacitorconductor 18 b with the insulating layer 16 interposed therebetween. Inaddition, a region in which the insulating layers 16 provided with thecapacitor conductors 18 are laminated is called an inner layer region.In addition, at a positive direction side of the inner layer region inthe y axis direction, insulating layers 16 each provided with nocapacitor conductor 18 are preferably laminated. At a negative directionside of the inner layer region in the y axis direction, insulatinglayers 16 each provided with no capacitor conductor 18 are preferablylaminated. Hereinafter, these two regions in which the insulating layers16 provided with no capacitor conductor 18 are laminated are each calledan outer layer region.

The external electrodes 14 a and 14 b are preferably provided directlyon the lower surface S6 of the laminate 12 so as to cover the exposedportions 26 a and 26 b, respectively. However, the external electrodes14 a and 14 b do not protrude from the lower surface S6 and are notprovided on the ridge lines L1 to L12. The external electrode 14 a islocated at the negative direction side in the x axis direction from theexternal electrode 14 b. The external electrodes 15 a and 15 b arepreferably provided directly on the upper surface S5 of the laminate 12so as to cover the exposed portions 28 a and 28 b, respectively. Theexternal electrodes 15 a and 15 b do not protrude from the upper surfaceS5 and are not provided on the ridge lines L1 to L12. The externalelectrode 15 a is located at the negative direction side in the x axisdirection from the external electrode 15 b. Since the externalelectrodes 14 a, 14 b, 15 a, and 15 b are arranged as described above,the capacity C is connected between the external electrodes 14 a and 15a and the external electrodes 14 b and 15 b. The external electrodes 14a, 14 b, 15 a, and 15 b may preferably be made of Cu, for example.

The electronic component 10 is preferably configured such thatdegradation in properties caused by moisture absorption of the laminate12 is prevented. Hereinafter, the external electrode 14 a will bedescribed by way of example. FIG. 3 is a plan view of the externalelectrode 14 a of the electronic component 10. In FIG. 3, since the leadportions 22 a are hidden by the external electrode 14 a, the leadportions 22 a are shown by dotted lines. FIG. 4 is a cross-sectionalstructural view of the electronic component 10 taken along the line A-Ain FIG. 3.

As shown in FIGS. 3 and 4, the external electrode 14 a preferably coversthe exposed portions 26 a of the lead portions 22 a. That is, an outeredge E of the external electrode 14 a preferably surrounds a portion inwhich the exposed portions 26 a are provided. Hereinafter, a distancebetween the outer edge E of the external electrode 14 a and the exposedportions 26 a is represented by a distance D. As shown in FIGS. 3 and 4,the distance D between the outer edge E of the external electrode 14 aand the exposed portions 26 a indicates a distance between a portion F1of the outer edge E parallel to the exposed portions 26 a and an exposedportion 26 a closest to the portion F1 and also indicates a distancebetween a portion F2 of the outer edge E perpendicular to the exposedportions 26 a and an end portion of each of the exposed portions 26 a.

In the electronic component 10 according to this preferred embodiment,the distance D is preferably approximately 0.8 μm or more, for example.That is, the outer edge E of the external electrode 14 a is preferablylocated approximately 0.8 μm or more from the exposed portions 26 a.Thus, the external electrode 14 a extends approximately 0.8 μm or morefrom a portion of the laminate 12 at which the exposed portions 26 a areexposed to the lower surface S6.

In addition, in the electronic component 10, when the humidityresistance is taken into consideration, the outer edge E of the externalelectrode 14 a is preferably extended as far as possible from theportion at which the exposed portions 26 a are provided. However, in theelectronic component 10, the external electrode 14 a preferably does notprotrude from the lower surface S6 and is not provided on the ridgelines L1 to L12. Thus, in the electronic component 10, the upper limitof the distance D between the outer edge E of the external electrode 14a and the exposed portions 26 a is determined by the range in which theexternal electrode 14 a does not protrude from the lower surface S6. Inthis preferred embodiment, the upper limit of the distance D ispreferably about 55.4 μm, for example. Since the external electrodes 14b, 15 a, and 15 b also have the same structure as that of the externalelectrode 14 a, a detailed description thereof is omitted.

The electronic component 10 is preferably mounted on a circuit board. Inparticular, the lower surface S6 on which the external electrodes 14 aand 14 b are provided or the upper surface S5 on which the externalelectrodes 15 a and 15 b are provided is preferably used as a mountingsurface and is disposed to face the circuit board. Subsequently, theexternal electrodes 14 a and 14 b or the external electrodes 15 a and 15b are soldered to lands provided on the circuit board. Accordingly, theelectronic component 10 is mounted on the circuit board.

Next, a method for manufacturing the electronic component 10 will bedescribed with reference to FIGS. 1 to 3.

After BaTiO₃, CaTiO₃, SrTiO₃ or CaZrO₃, for example, preferably used asa primary component and a Mn compound, a Fe compound, a Cr compound, aCo compound, or a Ni compound, for example, preferably used as anaccessory component are weighed at a predetermined ratio and are thencharged in a ball mill, wet mixing is performed. After an obtainedmixture is dried and is then pulverized, an obtained powder is calcined.After a calcined powder is wet-pulverized, drying and pulverizing aresequentially performed, so that a dielectric ceramic powder is obtained.

To this dielectric ceramic powder, an organic binder and an organicsolvent are preferably added, and mixing is then performed using a ballmill, for example. After a ceramic slurry is formed into sheets on acarrier sheet by, for example, a doctor blade method, drying isperformed so as to form ceramic green sheets which are to be formed intothe insulating layers 16. The thickness of each ceramic green sheetwhich is to be formed into the insulating layer 16 is preferably in arange of about 0.5 μm to about 10 μm.

Next, the capacitor conductors 18 a and 18 b are formed on the ceramicgreen sheets which are to be formed into the insulating layers 16preferably by applying a paste including a conductive material using amethod, such as a screen printing or a photolithographic method, forexample. As the paste including a conductive material, for example, apaste formed by adding an organic binder and an organic solvent to ametal powder may be used.

Next, the ceramic green sheets which are to be formed into theinsulating layers 16 are laminated, so that a green mother laminate isobtained. Subsequently, pressure bonding is preferably performed on thegreen mother laminate by a hydrostatic pressure press.

Next, the green mother laminate is preferably cut into a plurality ofgreen laminates 12 each having a predetermined size. Subsequently, abarrel polishing process is preferably performed on the surfaces of thelaminate 12, so that the corners and the ridge lines L1 to L12 of thelaminate 12 are chamfered.

Next, the green laminate 12 is fired. As a firing temperature, forexample, a temperature in a range of approximately 900° C. toapproximately 1,300° C. is preferable. With the steps described above, afired laminate 12 in which the capacitor conductors 18 are embedded isprepared.

Next, the external electrodes 14 a, 14 b, 15 a, and 15 b are preferablyformed by a plating method. In this preferred embodiment, the externalelectrodes 14 a, 14 b, 15 a, and 15 b are preferably formed by twomethods, that is, a strike plating method and a thick layer platingmethod.

The strike plating method is a method performed for a short time inorder to improve the adhesion and/or covering properties of a platinglayer. In the strike plating method, the laminate 12 is charged in abarrel including conductive media. Next, the barrel is immersed in aplating solution and is then rotated for a predetermined time.Accordingly, the conductive media come into contact with the exposedportions 26 a, 26 b, 28 a, and 28 b, so that an electrical power issupplied.

In the thick layer plating method, the laminate 12 is charged in abarrel including conductive media. Next, the barrel is immersed in aplating solution and is then rotated for a predetermined time.Accordingly, the conductive media come into contact with the exposedportions 26 a, 26 b, 28 a, and 28 b, so that an electrical power issupplied.

With the plating methods described above, the external electrodes 14 a,14 b, 15 a, and 15 b are formed on and around the exposed portions 26 a,26 b, 28 a and 28 b preferably to have a thickness of approximately 5μm, for example. In addition, by adjusting the processing time for thestrike plating method and that for the thick layer plating method, thedistance D shown in FIGS. 3 and 4 can be adjusted. With the stepsdescribed above, the electronic component 10 is completed.

With the electronic component 10, degradation in properties thereofcaused by moisture absorption of the laminate 12 is prevented.Particularly, in the multilayer electronic component disclosed inJapanese Unexamined Patent Application Publication No. 2008-47907, thedielectric material may be denatured by moisture absorption. As aresult, the insulating properties of the dielectric layers providedbetween the internal electrodes are degraded, and short circuiting mayoccur therebetween.

In the electronic component 10 of this preferred embodiment, theexternal electrodes 14 a, 14 b, 15 a, and 15 b function to preventmoisture absorption of the insulating layers 16 located directlythereunder. Thus, in the electronic component 10, the externalelectrodes 14 a, 14 b, 15 a, and 15 b extend by approximately 0.8 μm ormore from the portions at which the exposed portions 26 a, 26 b, 28 a,and 28 b are exposed to the upper surface S5 and the lower surface S6.Accordingly, moisture absorption of the insulating layers 16 providedbetween the capacitor conductors 18 is effectively prevented. As aresult, in the electronic component 10, degradation in propertiesthereof caused by moisture absorption of the laminate 12 is effectivelyprevented.

In addition, in the electronic component 10, the generation ofappearance defects of the external electrodes 14 a, 14 b, 15 a, and 15 bcan be prevented as described below. In more particular, in theelectronic component 10, the external electrodes 14 a, 14 b, 15 a, and15 b are preferably formed by a plating method so as to cover theexposed portions 26 a, 26 b, 28 a, and 28 b. In addition, when theprocessing time for the plating method is increased, the distances Dbetween the outer edges E of the external electrodes 14 a, 14 b, 15 a,and 15 b and the exposed portions 26 a, 26 b, 28 a, and 28 b can beincreased. Accordingly, the external electrodes 14 a, 14 b, 15 a, and 15b may preferably be formed, for example, on the ridge lines L2, L4, L10,and L12.

In this preferred embodiment, when the external electrodes 14 a, 14 b,15 a, and 15 b are formed by a plating method, a plating solutionpenetrates between the external electrodes 14 a, 14 b, 15 a, and 15 band the laminate 12. The plating solution as described above can beremoved by a heat treatment. However, as described below, when theexternal electrodes 14 a, 14 b, 15 a, and 15 b are formed on the ridgelines L2, L4, L10, and L12, an appearance defect called a blister mayoccur.

During the heat treatment, the external electrodes 14 a, 14 b, 15 a, and15 b are preferably heated to a greater extent than the laminate 12.Thus, although large heat shrinkage occurs in the external electrodes 14a, 14 b, 15 a, and 15 b, large heat shrinkage does not occur in thelaminate 12. Thus, at the ridge lines L2, L4, L10, and L12, the externalelectrodes 14 a, 14 b, 15 a, and 15 b generate a force so as to clamp tothe laminate 12. Accordingly, the external electrodes 14 a, 14 b, 15 a,and 15 b are more securely adhered to the laminate 12 at the ridge linesL2, L4, L10, and L12 than at the upper surface S5 and the lower surfaceS6. Thus, a plating solution vaporized during the heat treatment ispreferably confined between the external electrodes 14 a, 14 b, 15 a,and 15 b and the laminate 12 at the ridge lines L2, L4, L10, and L12. Asa result, the external electrodes 14 a, 14 b, 15 a, and 15 b are peeledaway from the laminate 12 by the vaporized plating solution so as togenerate blisters. That is, the external electrodes 14 a, 14 b, 15 a,and 15 b have appearance defects.

Thus, in the electronic component 10, the external electrodes 14 a, 14b, 15 a, and 15 b are preferably not provided on the ridge lines L2, L4,L10, and L12. Accordingly, the external electrodes 14 a, 14 b, 15 a, and15 b are prevented from having appearance defects. In addition, in thispreferred embodiment, chamfering is preferably performed on theelectronic component 10 by the barrel polishing process. Thus, the ridgelines L1 to L12 of the electronic component 10 have substantially roundshapes due to the chamfering.

In order to more confirm the advantages of the electronic component 10,the inventors of the present invention performed the followingexperiments. In particular, seven types of electronic components havingthe following conditions were formed.

-   Dimensions: about 1.0 mm×about 0.5 mm×about 0.5 mm-   Material for an insulating layer: Barium titanate-based dielectric    ceramic-   Number of insulating layers: 475 layers-   Number of insulating layers in an inner layer region: 445 layers-   Number of insulating layers in each outer layer region: 15 layers-   Thickness of each insulating layer: about 0.7 μm-   Material for a capacitor conductor: A metal including Ni as a    primary component.-   Rated voltage: about 4.0 V-   Electrostatic capacitance: about 10 μF

The barrel polishing-process conditions for forming the seven types ofelectronic components are shown below.

-   Operation method: Wet barrel polishing-   Number of revolutions: about 250 rpm-   Media: Zirconia ball (about 1.0 mm in diameter)-   POT volume: about 340 cc-   Time: about 30 minutes

One example of conditions of a strike plating method for forming theseven types of electronic components is shown below.

-   Plating solution: Copper pyrophosphate (about 14 g/L), potassium    pyrophosphate (about 120 g/L), potassium oxalate (about 10 g/L)-   Bath temperature: about 25° C.-   pH: about 8.5-   Barrel: Horizontal rotation barrel-   Number of revolutions: about 10 rpm-   Diameter of conductive media: about 0.5 mm-   Current density: about 0.11 A/dm²-   Time: about 30 minutes

One example of conditions of a thick layer plating method for formingthe seven types of electronic components is shown below.

Plating solution: “Pyrobright process (Pyrobright PY-61 bath)”manufactured by Uyemura & CO., LTD.

-   Bath temperature: about 55° C.-   pH: about 8.8-   Barrel: Horizontal rotation barrel-   Number of revolutions: about 10 rpm-   Diameter of conductive media: about 0.5 mm-   Current density: about 0.30 A/dm²-   Time: about 60 minutes

Among the seven types of electronic components, the distance D shown inFIGS. 3 an 4 was changed as shown in Table 1 below. In order to changethe distance D, the processing time for the strike plating method andthe processing time for the thick layer plating method were changed asshown in Table 1. Table 1 shows the relationship between the distance Dand the processing times of the first to the fifth examples and thefirst and the second comparative examples.

TABLE 1 Time for Time for Thick Distance Strike Plating Layer Plating D(μm) Method (min) Method (min) First Example 0.8 0 12 Second Example 5.30 75 Third Example 16.2 30 60 Fourth Example 34.1 60 50 Fifth Example55.4 110 30 First Comparative 0.7 0 10 Example Second Comparative 63.8130 30 Example

A humidity resistance test was performed on each of the electroniccomponents of the first to the fifth examples and the first and thesecond comparative examples, and the generation of appearance defectswas also checked. For the humidity resistance test, 100 electroniccomponents of each of the first to the fifth examples and the first andsecond comparative examples were formed, and a pressure cooker bias test(PCBT) was performed on 70 out of 100 electronic components each at atemperature of about 125° C., a relative humidity of about 95%, and avoltage of about 2.0 V for about 72 hours. Subsequently, the resistancebetween the external electrodes was measured, and an electroniccomponent having a resistance of about 1 MΩ or less was determined to bedefective. In addition, in order to check the generation of appearancedefects, the generation of blisters of all of 100 electronic componentswas checked by visual inspection. Table 2 shows experimental results,and the defect rate of the humidity resistance test and that of theappearance check are shown.

TABLE 2 Defect Rate of Defect Rate Humidity of Appearance ResistanceTest Check Judgment First Example 0/70 0/100 ◯ Second Example 0/70 0/100◯ Third Example 0/70 0/100 ◯ Fourth Example 0/70 0/100 ◯ Fifth Example0/70 0/100 ◯ First Comparative 1/70 0/100 X Example Second Comparative0/70 1/100 X Example

According to Table 2, in the first to the fifth examples in which thedistance D is in a range of about 0.8 μm to about 55.4 μm, no electroniccomponents were found to be defective in the humidity resistance testand the appearance check. On the other hand, in the electronic componentin which the distance D was about 0.7 μm, a defect was generated in thehumidity resistance test. In addition, in the electronic component inwhich the distance D was about 63.8 μm, an appearance defect wasgenerated. Accordingly, the distance D is preferably in a range of about0.8 μm to about 55.4 μm.

Hereinafter, an electronic component 10 a according to a modifiedpreferred embodiment of the present invention will be described withreference to the drawings. FIG. 5 is an appearance perspective view ofthe electronic component 10 a according to the modified preferredembodiment. FIG. 6 is an exploded perspective view of the laminate 12 ofthe electronic component 10 a according to the modified preferredembodiment.

Between the electronic component 10 and the electronic component 10 a,the shapes of the external electrodes 14 a, 14 b, 15 a, and 15 b and theshapes of the capacitor conductors 18 are different from each other.More specifically, in the electronic component 10 a, a lead portion 22′apreferably extends to the longer side of the insulating layer 16 at thenegative direction side in the z axis direction and also preferablyextends to the shorter side of the insulating layer 16 at the negativedirection side in the x axis direction. In addition, the lead portion22′a also preferably extends to a corner portion at which the longerside and the shorter side intersect with each other. As in the case ofthe lead portion 22′a, each of the lead portions 22′b, 24′a, and 24′balso preferably extend to the longer side and the shorter side of thecorresponding insulating layer 16 and to a corner portion at which thelonger side and the shorter side intersect with each other. Thecapacitor conductors 18 a and 18 b described above are provided on theridge lines L5 to L8.

The external electrodes 14 a, 14 b, 15 a, and 15 b are preferablyarranged so as to cover exposed portions 26′ and 28′ of the capacitorconductors 18. Thus, the external electrodes 14 a, 14 b, 15 a, and 15 bare preferably provided on the ridge lines L5 to L8. That is, among theridge lines L1 to L12 of the electronic component 10 a, the capacitorconductors 18 are preferably provided on only the ridge lines L5 to L8.

Even in the electronic component 10 a as described above, degradation inproperties thereof caused by moisture absorption of the laminate 12 areeffectively prevented as in the electronic component 10.

Furthermore, in the electronic component 10 a, although the externalelectrodes 14 a, 14 b, 15 a, and 15 b are provided on the ridge lines L5to L8, the generation of appearance defects are prevented. Morespecifically, the external electrodes 14 a, 14 b, 15 a, and 15 b arepreferably connected to the capacitor conductors 18 a and 18 b at theridge lines L5 to L8. Thus, during a heat treatment performed to removea plating solution, the external electrodes 14 a, 14 b, 15 a, and 15 bare prevented from shrinking. As a result, a plating solution vaporizedduring the heat treatment is prevented from being confined between theexternal electrodes 14 a, 14 b, 15 a, and 15 b and the laminate 12 atthe ridge lines L2, L4, L10, and L12. Accordingly, in the electroniccomponent 10 a, although the external electrodes 14 a, 14 b, 15 a, and15 b are provided on the ridge lines L5 to L8, the generation ofappearance defects is effectively prevented.

The present invention is not limited to the preferred embodimentsdescribed above and may be modified within the scope of the presentinvention.

FIG. 7 is a perspective view of an electronic component 10 b accordingto another modified preferred embodiment of the present invention. FIG.8 is an exploded perspective view of the laminate 12 of the electroniccomponent 10 b according to the another modified preferred embodiment.As shown in the electronic component 10 b of FIG. 7, the externalelectrodes 15 a and 15 b may preferably not be provided. In this case,as shown in FIG. 8, the lead portions 24 a and 24 b are also preferablynot provided.

In addition, in the electronic components 10, 10 a, and 10 b, thecircuit element embedded in the laminate 12 is not limited to thecapacitor C. Thus, as the circuit element, a piezoelectric component, aresistor, a coil, a thermistor, or other suitable circuit element, forexample, may preferably be used. When the circuit element is apiezoelectric component, for example, a piezoelectric crystal ceramic,such as a PZT-based ceramic, may preferably be used as a material forthe insulating layer 16. In addition, when the circuit element is athermistor, for example, a ceramic, such as a spinel-based ceramic, maypreferably be used as a material for the insulating layer 16.Furthermore, when the circuit element is a coil, for example, a magneticceramic may preferably be used as a material for the insulating layer16.

In addition, although being formed by a plating method as describedabove, the external electrodes 14 a, 14 b, 15 a, and 15 b may preferablybe formed by performing a plating method twice. In particular, after anunderlayer plating film is formed by a first plating method, an upperlayer plating film is then formed on the underlayer plating film by asecond plating method. A material for the underlayer plating film andthe upper layer plating film is preferably a metal selected from thegroup consisting of Cu, Ni, Sn, Pb, Au, Ag, Pd, Bi, and Zn or an alloyformed of at least two thereof, for example. When Ni is used as amaterial for the capacitor conductor 18, Cu, for example, which has goodcompatibility with Ni, is preferably used as the material for theunderlayer plating film. In addition, the upper layer plating film mayhave a two-layered structure which includes a first upper layer platingfilm and a second upper layer plating film. As a material for the firstupper layer plating film in contact with the underlayer plating film,Ni, for example, which is not likely to be eroded by a solder, ispreferably used. In addition, as a material for the second upper layerplating film exposed to the outside, Sn or Au, for example, which isexcellent in solder wettability, is preferably used. The thicknesses ofthe underlayer plating film, the first upper layer plating film, and thesecond upper layer plating film are each preferably in a range of about1 μm to about 15 μm.

As described above, the present invention is effectively applied toelectronic components and is particularly superior since degradation inproperties thereof caused by moisture absorption of a laminate isprevented.

While preferred embodiments of the present invention have been describedabove, it is to be understood that variations and modifications will beapparent to those skilled in the art without departing from the scopeand spirit of the present invention. The scope of the present invention,therefore, is to be determined solely by the following claims.

What is claimed is:
 1. An electronic component comprising: a laminateincluding a plurality of insulating layers laminated on each other; afirst internal conductor embedded in the laminate and including a firstexposed portion exposed between respective ones of the plurality ofinsulating layers at a predetermined surface of the laminate; and afirst plated external electrode provided directly on the predeterminedsurface by direct plating so as to cover the first exposed portion;wherein the first external electrode includes an outer peripheral edgethat is spaced away from the first exposed portion along thepredetermined surface of the laminate by about 0.8 μm to about 55.4 μm;the space between the outer peripheral edge and the first exposedportion is greater than a thickness of one of the plurality ofinsulating layers; the first exposed portion is arranged closer to theouter peripheral edge of the first external electrode than any otherexposed portions of internal conductors embedded in the laminate; andthe first internal conductor and the first external electrode are notprovided on ridge lines of the laminate at which respective sides of thelaminate are connected.
 2. The electronic component according to claim1, further comprising: a second internal conductor embedded in thelaminate and including a second exposed portion exposed betweenrespective ones of the plurality of insulating layers at a predeterminedsurface of the laminate; and a second plated external electrode provideddirectly on the predetermined surface by direct plating so as to coverthe second exposed portion; wherein the second external electrodeincludes an outer edge that is spaced away from the second exposedportion by about 0.8 μm or more.
 3. The electronic component accordingto claim 2, wherein the first internal conductor and the second internalconductor define a capacitor at a location at which the first internalconductor and the second internal conductor face each other with atleast one of the plurality of insulating layers interposed therebetween.4. The electronic component according to claim 1, wherein thepredetermined surface is a mounting surface of the laminate.
 5. Anelectronic component comprising: a laminate including a plurality ofinsulating layers laminated on each other; a first internal conductorembedded in the laminate and including a first exposed portion exposedbetween respective ones of the plurality of insulating layers at apredetermined surface of the laminate; and a first plated externalelectrode provided directly on the predetermined surface by directplating so as to cover the first exposed portion; wherein the firstexternal electrode includes an outer peripheral edge that is spaced awayfrom the first exposed portion along the predetermined surface of thelaminate by about 0.8 μm to about 55.4 μm; the space between the outerperipheral edge and the first exposed portion is greater than athickness of one of the plurality of insulating layers; the firstexposed portion is arranged closer to the outer peripheral edge of thefirst external electrode than any other exposed portions of internalconductors embedded in the laminate; and the first internal conductor isprovided on at least one of ridge lines of the laminate at whichrespective sides of the laminate are connected, and among the ridgelines of the laminate, the first external electrode is provided only onthe at least one ridge line on which the first internal conductor isprovided.
 6. The electronic component according to claim 5, furthercomprising: a second internal conductor embedded in the laminate andincluding a second exposed portion exposed between respective ones ofthe plurality of insulating layers at a predetermined surface of thelaminate; and a second plated external electrode provided directly onthe predetermined surface by direct plating so as to cover the secondexposed portion; wherein the second external electrode includes an outeredge that is spaced away from the second exposed portion by about 0.8 μmor more.
 7. The electronic component according to claim 6, wherein thefirst internal conductor and the second internal conductor define acapacitor at a location at which the first internal conductor and thesecond internal conductor face each other with at least one of theplurality of insulating layers interposed therebetween.
 8. Theelectronic component according to claim 5, wherein the predeterminedsurface is a mounting surface of the laminate.